Space Life Could Give You An Extra Head (If You’re A Flatworm)

An amputated flatworm fragment sent to space regenerated into a double-headed worm, a rare spontaneous occurrence of double-headedness. Credit: Junji Morokuma, Allen Discovery Center at Tufts University

Back in 2015, astronaut Scott Kelly traveled to the International Space Station (ISS) for a year-long stay, part of a landmark study looking at the physical changes that result from extended time in space. (His identical twin, Mark Kelly, remained on Earth for a comparison.) A few weeks before Kelly was scheduled to arrive at the ISS, a group of flatworms belonging to researchers at Tufts University were finishing up a five-week mission there. The researchers were curious to see how life off Earth affected the worms’ ability to regenerate their tails when cut.

When Kelly returned to Earth the following year, the physical changes he experienced were subtle. But living in space had a much more profound effect on the simple organism of the flatworm. In a study out this week, Tufts researcher Michael Levin describes how one of the space-faring worms generated not a tail, but a second head, likely the result of leaving Earth’s electromagnetic field. He joins Ira to discuss how living in space could affect the human body at a level we can’t yet see.

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IRA FLATOW: This is Science Friday. I’m Ira Flatow. The astronaut Scott Kelly spent a full year on the International Space Station. And one of the big questions was whether living in space would result in any physical changes to his body.

A few weeks before Kelly was scheduled to arrive, a group of flatworms was finishing up its own five-week mission there. And researchers were curious about a similar idea. Would the worms regrow their tails in space the same way they do on Earth?

The changes NASA scientists recorded in Kelly when he came home weren’t easy to detect. But the worms, oh, they’re a different story. Leaving Earth caused one of the worms to grow a second head. That’s what I said. A second head.

And there were other changes too, which could show us how living in space could be messing– might be messing with the human body at a level we can’t see yet, or won’t see for maybe years to come. Joining me to discuss is my guest Michael Levin, professor of biology and director of the Allen Discovery Center at Tufts University. Welcome to Science Friday.

MICHAEL LEVIN: Thank you, Ira. It’s a pleasure to be here.

IRA FLATOW: Oh, thank you. Why use flatworms to study the effects of space travel when we can use people like Scott and his brother Mark?

MICHAEL LEVIN: Well, these flatworms do an amazing trick that people have not learned yet, which is to regenerate any part of their body when damaged. But I should also say that the purpose of this research was not only about space travel. The fact is that what we learn about how cells communicate with each other to be able to form complex structures, and how physical forces such as loss of gravity, loss of the geomagnetic field, and so on, effect this process is going to be useful for regenerative medicine therapies on Earth, as well as teaching us about biology in space.

IRA FLATOW: So it appears that when you say loss of gravity, loss of the magnetic field, when these flatworms came back with second head, did you relate those two things?

MICHAEL LEVIN: Well, one of the ways that cells use to decide what structure they’re going to build in any particular part of the body is a set of electrical communications, so that’s what my lab studies is electrical communication among cells. And it’s quite likely that some of the forces that these animals experienced in space, both vibrational, magnetic, gravitational, and so on, were responsible for deranging the normal communication that allows the cells to know to make exactly one head and one tail in the appropriate location.

IRA FLATOW: Give me some details. That’s fascinating. How does a flatworm use the magnetic field to know about growing a head and tail?

MICHAEL LEVIN: Well, the magnetic field, we actually don’t know. This is the interesting part of this research is that we actually don’t know yet how the experience of space travel affected the electrical communication. But we know quite a bit about how flatworm cells and cells in other organisms use electrical messages that they send to each other to decide what anatomical structures they’re going to build.

IRA FLATOW: Mm-hmm. So the absence of that sort of screws up the whole circuitry that’s going on in the flatworm?

MICHAEL LEVIN: It’s possible. We actually don’t know that part yet. Basically, we got these worms back. We were not able to interact with them during the four weeks that they were up on the Space Station, so we didn’t have access to the immediate early events of regeneration. We were only able to study them after they’ve come down. But it is quite likely that some of these experiences derange the physiological circuitry that is used by these animals to regenerate properly.

IRA FLATOW: Now, why weren’t then all the flatworms affected the same way?

MICHAEL LEVIN: Well, that’s an excellent question. And actually, this is something that– variability among biological systems is something that is a big mystery. And lots of people study the question of why, for example, certain medical treatments affect different patients differently or have different side effects in different people. But biological systems are not cookie-cutter. Even these planaria, which are genetically identical to each other because they all come from one parent worm, still in the lab we see significant differences in how they respond to chemical treatments, to behavioral [INAUDIBLE]. These worms even have individualized personalities. And there’s quite a bit of variation. And this is something that we’re just beginning to understand.

IRA FLATOW: Would never have guessed that a worm has an individual personality, but I’m glad you told us about that. Oh,

MICHAEL LEVIN: Yeah. Yeah.

IRA FLATOW: Yeah. Once they got back on Earth, besides the two heads, did you notice any other changes that were–

MICHAEL LEVIN: Yes. There was a whole set of differences. And remarkably, these differences persisted almost two years after their return to Earth. So one of the changes was behavioral, so the way they react to light and the way that normal worms avoid light exposure was different in these worms. They had behavioral changes.

They had changes in their microbiome. So the bacteria that normally live on these animals, the distribution of species was quite a bit different, as well as we found differences in the water itself, so there were certain proteins that these animals secreted into the water that were quite different in the space traveling worms versus the Earth-bound controls.

IRA FLATOW: Could there be subtle changes in astronauts then who are up for a year or a long time in space that we haven’t seen on their cellular level yet, or it may take time to develop?

MICHAEL LEVIN: Yes. That’s entirely possible. And one of the recent projects that we published on is the fact that there can be changes in the physiological circuitry of these animals that are basically undetectable until a round of regeneration is required sometime in the future. That is, animals will look perfectly normal but when they are damaged and asked to regenerate, a different result happens because of the way that these physiological circuits were changed. So something like that could be caused by the experience of space travel, sure.

IRA FLATOW: You mentioned that your research has a lot more to do than just space travel. What do you learn from these flatworms that could be applied to other areas?

MICHAEL LEVIN: Well, actually these flatworms are models of many things, from neurodegenerative diseases to regenerative medicine. So for example, the fact that they’re able to regenerate any part of their body, including their brain and central nervous system, will help us to develop treatments for injury and degenerative disease.

These worms appear to have solved the aging problem as well. There’s no evidence of aging in individual planaria. They seem to pretty much go on forever.

IRA FLATOW: Wait. Let me just stop you right there for a second. You mean a flatworm can live forever?

MICHAEL LEVIN: That’s correct. There’s no real sense to the question of how old a given flatworm is. They regenerate their bodies as needed. Cells turn over. But the animal seems to go on forever as far as we can tell.

IRA FLATOW: Wow. Do we know any other animal that does that?

MICHAEL LEVIN: I believe for example hydra, the invertebrate hydra. And there may be other marine invertebrates that do this. But planaria are really a unique model.

But they’re telling us is that it’s possible. They’re literally telling us that it may be possible to live forever, to be a complex organism with a brain, behavior, and all of those things, and live forever.

IRA FLATOW: Wow. Maybe that’s good news. I’m not sure. But what else would you like to know? I mean, if you could do the experiment again, would you like to tweak it for the next time? What would you like to do?

MICHAEL LEVIN: Yeah. Well, we’re planning another mission with our collaborators at the Space Tango and the Kentucky Space institute, where we’re hoping for another mission. And there’s a few things we would like to do differently this time.

One of the things that would be really nice is to be able to have either the astronauts or some sort of automated device interact with the worms while they are in space, so to cut them while they are in space, because we have to do the amputations here on Earth before handing the sample over to the crew. So it would be nice to be able to have them cut in space. And also increased measurements done while they are in space so that we could observe what’s happening to the worms, get readings of the geomagnetic field exposure, of the vibration, radiation, all those things during the experience.

IRA FLATOW: That’s exciting. Well, let us know when you do this again, OK?